Osteoarthritis is a disease that affects the joints. When intra-articular cartilage of the joints is damaged or worn, it causes osteoarthritis, and thus affects joint stiffness, pain and loss of function. Osteoarthritis commonly occurs in hip joint, knee joint, spinal joint and joints of the hand (such as palm and thumb joint). Among these, the carpometacarpal (CMC) joint arthritis is one of the most important issue in the degenerative arthritis disease of the upper limb. The CMC joint is located at the base portion of the thumb in anatomy, wherein a distal end of the CMC joint is a metacarpal bone, and a proximal end thereof is a trapezium close to the radial side. The CMC joint is the most activity joint of hand joints and can stretch, bend, adduct, abduct and rotate. Thus, once the CMC joint is degenerated, lesioned or wounded, it will cause great influence in daily life.
When the medicament or injection can't be effective to relieve pain and can't further deal with the degenerative arthritis of the CMC joint, the doctor generally advise the patient to be treated by a hand joint surgery. Further, the design of the artificial implant and the development of material fabrication thereof are continuously improved, so that artificial implants are applied to clinical use day by day. The injured CMC joint is replaced by arthroplasty surgery, and thus it not only reduces pain from arthritis, but also maintains the CMC joint activities and the behavior function of hand.
Briefly, the arthroplasty is a surgically method for reducing the pain from arthritis and restoring the joint function. The process of a traditional surgery for replacing an artificial CMC joint is firstly to crosscut a wound from the root of the thumb, then temporarily cut and remove the tendon of a abductor pollicis longus (APL) attached to the trapezium, open a joint capsule of the CMC joint, and abscise the damaged CMC joint surface at the proximal end of a first metacarpal to form an incision. Then, a portion of an implant is inserted into a bone marrow cavity of the first metacarpal from the incision at the proximal end of the first metacarpal. Thereafter, a surgical suture is used to reconstruct the APL tendon cut during the surgery, followed by suturing the wound.
However, during the surgery, it not only needs to temporarily cut the APL in the step of moving the APL tendon originally attached to the trapezium, but also needs to drill the first metacarpal to form two small holes for the surgical suture to pass therethrough, in order to arrange the surgical suture at both sides of the APL in advance. Thus, after the artificial implant is implanted into the bone marrow cavity, the APL tendon can be attached on the outer surface of the first metacarpal by surgical suturing. As mentioned above, the steps of cutting the APL tendon or drilling holes on the first metacarpal both are to destroy the tissue of the metacarpal or the tendon before reconstruction. In addition, the surgical suture arranged in advance is easily over-pushed into the bone marrow cavity by the artificial implant when the artificial implant is implanted into the bone marrow cavity. This causes the displacement of the surgical suture and thus it is difficult to carry out the precise positioning. Alternatively, the surgical suture arranged in advance may be destroyed by the artificial implant when the artificial implant is implanted into the bone marrow cavity, it's thus more difficult to process the reconstruction surgery for the APL tendon.
Therefore, it is necessary to provide an artificial implant for a carpometacarpal joint for solving the problems existing in the foregoing conventional technique.